Which medication is indicated for the treatment of type 2 diabetes?

Metformin hydrochloride is a medication that is specifically indicated for the management of type 2 diabetes mellitus. It functions primarily by improving insulin sensitivity and decreasing hepatic glucose production, which helps lower blood sugar levels in individuals with this condition. Metformin is often the first-line treatment prescribed for type 2 diabetes because of its effectiveness in regulating blood glucose without causing significant weight gain, which can often be a concern for patients.

In contrast, simvastatin is used primarily to lower cholesterol levels and reduce the risk of cardiovascular disease, rather than controlling blood sugar levels. Levothyroxine sodium is a thyroid hormone replacement medication that is used for treating hypothyroidism, and it is not relevant to the management of diabetes. Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor used primarily for managing hypertension and heart failure, but it does not have a direct role in diabetes treatment.

Thus, metformin is the appropriate and targeted therapy among the options listed for treating type 2 diabetes, making it the correct choice.